The High Cost Of Waiting

A recent study in Nature finds that “political choices that delay mitigation” are the biggest factor making climate change unstoppable. Steve Hatfield-Dobbs discusses [paywalled] the implications for efforts to slow warming:

The study’s key message reinforces previous findings that urgent and more ambitious global action is required to maintain any chance of limiting global warming to 2 °C. The clear finding that the world would be better off acting from 2015 rather than 2020 also raises sharp and serious questions about the trade-offs implicit in the current pace of global negotiations and action. The window for effective action on climate change is closing quickly, and Rogelj et al. have put a price tag on each year of delay.

Keywan Riahi, IIASA energy program leader and study co-author said, “With a twenty-year delay, you can throw as much money as you have at the problem, and the best outcome you can get is a fifty-fifty chance of keeping temperature rise below two degrees.” Two degrees is the level that is currently supported by over 190 countries as a limit to avoid dangerous climate change.

The study indicated that an immediate global price of $20 a ton on emissions of carbon dioxide (CO2), the main greenhouse gas, would give a roughly 60 percent chance of limiting warming to below 2C.Wait until 2020 and the carbon price would have to be around $100 a ton to retain that 60 percent chance, Riahi told Reuters of the study made with other experts in Switzerland, New Zealand, Australia and Germany.